Vertical Pump

Abstract

To provide a vertical pump capable of suppressing a dry operation state of a sliding surface of a mechanical seal even when used under high-temperature and high-pressure environment.SOLUTION: A vertical pump 1 comprises: a rotational shaft 2 extending in a vertical direction; an impeller 3 fixed to a rotational shaft 2; a cylindrical casing 11 housing the impeller 3; a bracket 31 having a lid part 32 that closes the upper opening of the casing 11, and a cylindrical part 33 that protrudes upward from the lid part 32 and is arranged so that the rotational shaft 2 is inserted therethrough; and a mechanical seal 40 that seals the gap between the rotational shaft 2 and the cylindrical part 33. A sliding surface 40a of the mechanical seal 40 is positioned inside the cylindrical part 33.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vertical pump. [Background technology]

[0002] Conventionally, a vertical pump described in Patent Document 1 below has been known. The vertical pump includes a rotating shaft extending in the vertical direction, an impeller fixed to the rotating shaft, a cylindrical casing that houses the impeller, a bracket having a lid that closes an upper opening of the casing and a through hole through which the rotating shaft is inserted in the lid, and a mechanical seal that seals between the rotating shaft and the through hole. The mechanical seal has a fixed part fixed to the bracket and a rotating part fixed to the rotating shaft, and seals the periphery of the rotating shaft with the sliding surface between the fixed part and the rotating part as a seal surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-75476 A Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional vertical pumps, the sliding surface of the mechanical seal is located inside the casing and exposed to the pumped liquid (see reference numeral 11 in FIG. 1 of Patent Document 1). Vertical pumps are sometimes used in high-temperature and high-pressure environments, such as in boilers, and in such cases, the sliding surface of the mechanical seal is prone to running dry. When the pump runs dry, the sliding surface wears out, the pumped liquid leaks due to the wear, and the sliding surface is stabilized (sealing ability is restored) due to the leaking of the pumped liquid. This cycle of wear on the sliding surface shortens the life of the mechanical seal, and there is a problem in that maintenance such as replacement and repair becomes more frequent.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide a vertical pump that can suppress the dry running state of the sliding surface of the mechanical seal, even when used in a high temperature and high pressure environment. [Means for solving the problem]

[0006] A vertical pump according to one embodiment of the present invention comprises a rotating shaft extending in a vertical direction, an impeller fixed to the rotating shaft, a cylindrical casing that houses the impeller, a cover that closes an upper opening of the casing, and a bracket that protrudes upward from the cover and has a cylindrical portion through which the rotating shaft is inserted, and a mechanical seal that seals a gap between the rotating shaft and the cylindrical portion, and the sliding surface of the mechanical seal is located inside the cylindrical portion.

[0007] In the vertical pump, the cylindrical portion may be provided with an air vent plug at a position equal to or higher than the height of the sliding surface of the mechanical seal.

[0008] The vertical pump may further include a pumped fluid circulation structure that forms a circulating flow that guides the pumped fluid inside the casing to the sliding surface of the mechanical seal inside the cylindrical portion.

[0009] In the above vertical pump, the handled liquid circulation structure may include an inner cylindrical member disposed inside the cylindrical portion and surrounding the outside of the sliding surface of the mechanical seal, and a second impeller fixed to the rotating shaft and forming the circulating flow with either the inside or the outside of the inner cylindrical member as an outgoing path and the other as a return path.

[0010] In the vertical pump, the inner cylinder member may be fixed to the bracket.

[0011] In the vertical pump, the inner cylinder member may be fixed to the second impeller and rotate together with the second impeller.

[0012] In the vertical pump, the second impeller may form the circulating flow with an outward path on the outside of the inner cylindrical member and a return path on the inside of the inner cylindrical member.

[0013] The vertical pump may further include a third impeller fixed to the rotary shaft for air-cooling the cylindrical portion from the outside. Effect of the Invention

[0014] According to the above aspect of the present invention, it is possible to provide a vertical pump that can suppress a dry running state of the sliding surface of the mechanical seal even when used in a high temperature and high pressure environment. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view of a vertical pump according to a first embodiment. [Diagram 2] 1 is a cross-sectional view of the vicinity of a cylindrical portion of a vertical pump according to a first embodiment. FIG. [Diagram 3] FIG. 4 is a plan view of a second impeller according to the first embodiment. [Figure 4] 2 is a cross-sectional view of an inner cylinder member according to the first embodiment. FIG. [Diagram 5] FIG. 2 is a plan view of the inner cylinder member according to the first embodiment. [Figure 6] FIG. 11 is a cross-sectional view of the vicinity of a cylindrical portion of a vertical pump according to a second embodiment. [Figure 7] FIG. 6 is a cross-sectional view of a handled fluid circulation structure according to a second embodiment. [Figure 8] FIG. 11 is a plan view of a handled fluid circulation structure according to a second embodiment. [Figure 9] FIG. 11 is a cross-sectional view of the vicinity of a cylindrical portion of a vertical pump according to a third embodiment. [Figure 10] FIG. 11 is a cross-sectional view of the vicinity of a cylindrical portion of a vertical pump according to a fourth embodiment. [Figure 11] FIG. 11 is a plan view of a handled fluid circulation structure according to a fourth embodiment. [Figure 12] FIG. 11 is a cross-sectional view of the vicinity of a cylindrical portion of a vertical pump according to a fifth embodiment. [Figure 13]FIG. 13 is a plan view showing a third impeller according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] (First embodiment) FIG. 1 is a cross-sectional view of a vertical pump 1 according to a first embodiment. The vertical pump 1 shown in Fig. 1 is a vertical multi-stage pump including a rotating shaft 2 extending in the vertical direction and a plurality of impellers 3 fixed to the rotating shaft 2. The configuration of this vertical multi-stage pump will be described below, but it may be in a form having only one impeller 3. In addition, in the following description, the direction in which the central axis O of the rotating shaft 2 extends is referred to as the axial direction, the direction perpendicular to the central axis O is referred to as the radial direction, and the direction rotating around the central axis O is referred to as the circumferential direction.

[0018] The impeller 3 has a main plate 4, a side plate 5, and a plurality of blades 6. The main plate 4 is formed in a disk shape centered on a central axis O, and is fixed to the rotating shaft 2. The side plate 5 is formed in an annular shape coaxial with the main plate 4, and is disposed with a gap between it and the main plate 4 in the axial direction. The main plate 4 and the side plate 5 are connected via the plurality of blades 6. The space surrounded by the main plate 4, the side plate 5, and the plurality of blades 6 forms a flow path that guides the handled liquid in the radial direction. The side plate 5 forms an intake port 7 of the impeller 3.

[0019] The vertical pump 1 includes a cylindrical casing 11 that houses an impeller 3. The casing 11 defines a pump chamber 10A inside, in which the pumped liquid is pressurized by the impeller 3. The casing 11 includes an intermediate casing 11a stacked in multiple stages, an upper casing 11b disposed on the upper side of the intermediate casing 11a, a lower casing 11c disposed on the lower side of the intermediate casing 11a, and an outer casing 11d disposed outside the intermediate casing 11a and the upper casing 11b.

[0020] The intermediate casing 11a is formed into a bottomed cylindrical shape by press forming a steel plate or the like, and an opening through which the rotating shaft 2 is inserted is formed in the center of the bottom. The intermediate casings 11a are stacked in multiple stages according to the number of impellers 3. A return plate 12 is attached by welding to the lower surface of the bottom of the intermediate casing 11a. In addition, return vanes 13 are attached by welding to the lower surface of the return plate 12. A liner ring 14 is attached to the inner wall of the bottom opening of the intermediate casing 11a to prevent leakage of the handled liquid from around the suction port 7 of the impeller 3.

[0021] The upper casing 11b is formed in a bottomed cylindrical shape similar to the intermediate casing 11a, and is stacked on the uppermost stage of the intermediate casing 11a. A plurality of communication holes 11b1 are formed in the peripheral wall of the upper casing 11b. The outer casing 11d is formed in a cylindrical shape surrounding the radial outside of the intermediate casing 11a and the upper casing 11b. The outer casing 11d forms an annular flow path 10B that communicates with the communication holes 11b1 on the radial outside of the intermediate casing 11a and the upper casing 11b. The upper parts of the upper casing 11b and the outer casing 11d are covered by a casing cover 11e disposed on the lower surface of the bracket 31.

[0022] The lower casing 11c forms a communication space 10C that communicates with the suction port 7 at the lower end of the pump chamber 10A, and also forms a communication space 10D (second communication space) that communicates with the annular flow path 10B inside the outer casing 11d. The lower casing 11c has a first frame 11c1 that forms the communication space 10C on the inside, and a second frame 11c2 that surrounds the outside of the first frame 11c1 and forms the communication space 10D between itself and the first frame 11c1.

[0023] The first frame 11c1 is formed in a bottomed cylindrical shape (approximately dish-shaped) including a flange portion 11c4 in which a communication hole 11c3 is formed. The communication hole 11c3 penetrates the flange portion 11c4 in the axial direction and communicates the annular flow path 10B with the communication space 10D. The second frame 11c2 is formed in a bottomed cylindrical shape that accommodates the first frame 11c1 in a nested manner. The outer edge of the flange portion 11c4 of the first frame 11c1 comes into contact with the inner peripheral surface of the second frame 11c2, forming a gap (communication space 10D) between the outer peripheral surface of the first frame 11c1 and the inner peripheral surface of the second frame 11c2.

[0024] The lower casing 11c has a suction nozzle 21 extending horizontally and a discharge nozzle 22 extending horizontally. The suction nozzle 21 penetrates and is joined to the peripheral wall of the second frame 11c2, penetrates and is joined to the peripheral wall of the first frame 11c1, and extends to the communication space 10C. The discharge nozzle 22 is disposed on the same straight line as the suction nozzle 21, penetrates and is joined to the peripheral wall of the second frame 11c2, does not penetrate and is connected to the communication space 10D.

[0025] A pump stand 23 is provided below the lower casing 11c. The pump stand 23 is axially connected to the bracket 31 by a casing bolt 23a and a nut 23b. A plurality of the casing bolts 23a and nuts 23b are provided at intervals in the circumferential direction. By fastening the plurality of casing bolts 23a and nuts 23b, the multiple stages of the intermediate casing 11a, the upper casing 11b, the lower casing 11c, and the casing cover 11e are clamped in the axial direction.

[0026] The bracket 31 has a lid portion 32 that closes the upper opening of the casing 11, and a tubular portion 33 that is provided so as to protrude upward from the lid portion 32 and through which the rotating shaft 2 is inserted. The bracket 31 also has a pair of legs 34 (the legs 34 on the near side in FIG. 1 are not shown) that are provided radially outside the tubular portion 33 and protrude upward from the lid portion 32, and a base portion 35 supported by the pair of legs 34.

[0027] The base portion 35 supports a motor (not shown). The output shaft of the motor (not shown) is connected to the upper end of the rotating shaft 2 protruding upward from the cylindrical portion 33 via a coupling (not shown). The coupling (not shown) is surrounded by a pair of guard members 36 that are screwed to a pair of legs 34.

[0028] An air vent plug 37 and a priming plug 38 are provided on the cover portion 32 radially outward of the cylindrical portion 33. An air vent plug 39 (second air vent plug) is also provided on the cylindrical portion 33. A mechanical seal 40 is attached to the cylindrical portion 33. The mechanical seal 40 seals the gap between the rotating shaft 2 and the cylindrical portion 33, and prevents the pumped fluid from leaking from the pump chamber 10A through the cylindrical portion 33 to the outside of the machine.

[0029] In the vertical pump 1 configured as described above, when the impeller 3 rotates, the pumped liquid is sucked into the communication space 10C of the lower casing 11c through the suction nozzle 21. The pumped liquid sucked into the communication space 10C is sucked into the first-stage impeller 3 through the suction port 7 at the lower end of the pump chamber 10A and is pressurized. The pumped liquid discharged from the first-stage impeller 3 passes through a flow path formed by the return vane 13 and the return plate 12 and is guided to the suction port 7 of the next-stage impeller 3.

[0030] The pumped fluid is pressurized in multiple stages by the multiple impellers 3, and then flows into the upper casing 11b. The pumped fluid that has flowed into the upper casing 11b flows downward through the communication hole 11b1 and the annular flow passage 10B formed on the outside of the upper casing 11b, and flows into the communication space 10D through the communication hole 11c3. The pumped fluid that has flowed into the communication space 10D is discharged through the discharge nozzle 22 connected to the lower casing 11c.

[0031] FIG. 2 is a cross-sectional view of the vicinity of the cylindrical portion 33 of the vertical pump 1 according to the first embodiment. 2, the mechanical seal 40 is attached to the cylindrical portion 33 of the bracket 31. The mechanical seal 40 has a fixed portion 41 fixed to the bracket 31 side, and a rotating portion 42 fixed to the rotating shaft 2 side. Note that the mechanical seal 40 in this embodiment is a cartridge type in which the fixed portion 41 and the rotating portion 42 are detachable together, but it does not have to be of the cartridge type.

[0032] The fixed part 41 includes a fixed ring 43 (sliding member) that forms a sliding surface 40a that seals the periphery of the rotating shaft 2, and a holder 44 that holds the fixed ring 43. The sliding surface 40a is formed on the lower end surface of the fixed ring 43. A step is formed on the outer circumferential surface of the fixed ring 43, on which an O-ring 45 is disposed. This O-ring 45 provides a seal between the fixed ring 43 and the holder 44.

[0033] The holder 44 surrounds the outer circumferential surface of the fixed ring 43 and restricts the upward axial movement of the fixed ring 43 via an O-ring 45. The holder 44 has a bottom 44a having an opening, a side wall 44b extending upward from the peripheral edge of the bottom 44a, and a flange 44c extending radially outward from an upper end of the side wall 44b.

[0034] The rotating shaft 2 and a sleeve 49 (described later) are inserted through the opening of the bottom 44a with a space therebetween. The fixed ring 43 is held on the inner wall surface of the opening of the bottom 44a. The side wall 44b is an annular wall extending from the peripheral edge of the bottom 44a to the upper end of the cylindrical portion 33. An annular groove is formed on the outer wall surface of the side wall 44b in which an O-ring 45 is disposed to seal a gap with the casing cover 11e that extends to the inner wall surface of the cylindrical portion 33.

[0035] The flange portion 44c is formed in an annular shape extending radially outward from the upper end of the side wall portion 44b. The flange portion 44c is in contact with the peripheral edge of the upper opening of the tubular portion 33. The flange portion 44c is fixed to the tubular portion 33 in the axial direction by bolts 46 (fixing portion fixing parts). A plurality of bolts 46 are provided at intervals in the circumferential direction, and fix the flange portion 44c to the tubular portion 33 at a plurality of points.

[0036] The rotating part 42 has a rotating ring 47 (a mating sliding member) that faces the fixed ring 43 and forms the sliding surface 40a, a sleeve 49 that supports the rotating ring 47 on its outer periphery via a holder 48, a spring 50, and a second impeller 62 (described later) and through which the rotating shaft 2 is inserted on its inner periphery, and a sleeve presser 51 that fixes the sleeve 49 to the rotating shaft 2. The upper end surface of the rotating ring 47 that faces the fixed ring 43 in the axial direction forms the sliding surface 40a.

[0037] The gaps between the rotating ring 47 and the holder 48, between the holder 48 and the sleeve 49, and between the sleeve 49 and the rotating shaft 2 are sealed by O-rings 45. The holder 48 surrounds the outer circumferential surface of the rotating ring 47 and supports the rotating ring 47 from below via the O-ring 45. A spring 50 biases the holder 48 upward, pressing the rotating ring 47 towards the fixed ring 43.

[0038] The sleeve 49 is formed in a cylindrical shape and is fitted around the rotary shaft 2. The lower end of the sleeve 49 expands radially outward, and the upper surface of the expanded diameter portion supports the second impeller 62. The spring 50 is disposed in the axial gap between the holder 48 and the second impeller 62, and biases the holder 48 upward and presses the second impeller 62 against the expanded diameter portion of the sleeve 49 to fix it.

[0039] The lower end surface of the sleeve 49 is in axial contact with a ring holder 2a fixed to the rotating shaft 2. The ring holder 2a is a shaft part that determines the axial position of the mechanical seal 40. On the inside of the ring holder 2a, a split ring 2b that determines the axial position of the ring holder 2a is attached to an annular groove formed on the rotating shaft 2. This sleeve 49 passes through the inside of the rotating ring 47 and the fixed ring 43, and extends from the pump chamber 10A (inside the machine) to outside the machine.

[0040] The sleeve retainer 51 is welded to the upper end of the sleeve 49. The sleeve retainer 51 is formed in an annular shape, and a plurality of set screws 52 (rotating unit fixing parts) are screwed into the sleeve 49 at intervals in the circumferential direction. The sleeve 49 is provided with through holes at positions corresponding to the set screws 52, and the rotating shaft 2 can be tightened in the radial direction by screwing in the set screws 52. This fixes the rotating unit 42 to the rotating shaft 2, and the rotating unit 42 becomes rotatable together with the rotating shaft 2.

[0041] The sliding surface 40a of the mechanical seal 40 is located inside the cylindrical portion 33. That is, the sliding surface 40a of the mechanical seal 40 is located higher than the casing 11 (pump chamber 10A). The cylindrical portion 33 is provided with a second air vent plug 39 at a position equal to or higher than the height of the sliding surface 40a of the mechanical seal 40. Since the second air vent plug 39 is located at a position equal to or higher than the height of the sliding surface 40a of the mechanical seal 40, priming water can be injected up to the sliding surface 40a of the mechanical seal 40.

[0042] The vertical pump 1 is equipped with a pumped liquid circulation structure 60 that, during operation, forms a circulating flow (indicated by arrows in FIG. 2) that guides the pumped liquid inside the casing 11 (pump chamber 10A) to the sliding surface 40a of the mechanical seal 40 inside the cylindrical portion 33. The pumped liquid circulation structure 60 is equipped with an inner cylindrical member 61 that is disposed inside the cylindrical portion 33 and surrounds the outside of the sliding surface 40a of the mechanical seal 40, and a second impeller 62 that is fixed to the rotating shaft 2 and forms a circulating flow with either the inside or the outside of the inner cylindrical member 61 (the inside in FIG. 2) as the forward path and the other (the outside in FIG. 2) as the return path.

[0043] Fig. 3 is a plan view of the second impeller 62 according to the first embodiment. Fig. 4 is a cross-sectional view of the inner cylinder member 61 according to the first embodiment. Fig. 5 is a plan view of the inner cylinder member 61 according to the first embodiment. As shown in FIG. 3, the second impeller 62 includes a cylindrical mounting tube portion 62a and a plurality of blades 62b provided on the outer circumferential surface of the mounting tube portion 62a.

[0044] The mounting cylinder portion 62a is fitted onto the sleeve 49 as shown in Fig. 2. The multiple blades 62b have a vane shape of an axial fan, and send out the handled liquid in the pump chamber 10A toward the inside of the inner cylinder member 61. Note that, as long as the circulating flow shown in Fig. 2 can be formed as a result, the second impeller 62 may be, for example, a centrifugal fan instead of an axial fan.

[0045] The inner tube member 61 is formed in a cylindrical shape, as shown in Fig. 4, and is provided at its lower end with an annular flange 61a extending radially outward. The flange 61a is formed with a plurality of holes 61b spaced apart in the circumferential direction, as shown in Fig. 5. The holes 61b are formed in an arc shape along the outer circumferential surface of the inner tube member 61.

[0046] 2, the inner cylinder member 61 is fixed to the bracket 31. An annular groove 11e1 recessed radially outward is formed in a casing cover 11e forming an inner wall surface of the bracket 31. The outer peripheral end of a flange 61a of the inner cylinder member 61 fits into the annular groove 11e1 of the casing cover 11e.

[0047] The flange 61a is formed with a hole 61b penetrating in the axial direction, so that the handled fluid flowing outside the inner cylinder member 61 can pass through the flange 61a. The hole 61b may be a cutout portion cut out to the outer circumferential end of the flange 61a. In this embodiment, the outer circumferential end of the flange 61a is not cut out, so that the contact area with the annular groove 11e1 is secured all around, and the stability of the attachment of the inner cylinder member 61 is improved.

[0048] The inner diameter of the inner cylinder member 61 is larger than the outer diameter of the rotating portion 42 of the mechanical seal 40. The outer diameter of the inner cylinder member 61 is smaller than the inner diameter of the casing cover 11e that forms the inner wall surface of the cylindrical portion 33. The inner cylinder member 61 extends in the axial direction from a position near the base of the cylindrical portion 33 to a position equal to or higher than the height of the sliding surface 40a of the mechanical seal 40. An axial gap is formed between the upper end of the inner cylinder member 61 and the fixed portion 41 of the mechanical seal 40.

[0049] The following describes the wear loop caused by the dry operation state of the sliding surface 40a of the mechanical seal 40 configured as described above. In high temperature and pressure environments such as those used in boilers, the sliding surface 40a of the mechanical seal 40 is prone to enter a dry operation state, and wear of the sliding surface 40a, leakage of liquid due to wear, and stabilization of the sliding surface 40a due to the leakage of liquid (restoration of sealing properties) are repeated.

[0050] Specifically, when the sliding surface 40a of the mechanical seal 40 is in a dry operating state, or when external factors such as pressure fluctuations are added, the mechanical seal 40 comes into contact with the sliding surface 40a on one side, and wears at a faster pace than usual. As a result, as the wear progresses, liquid leaks from the sliding surface 40a, and if this state continues, the liquid leaks fortunately, and water lubrication is sufficient. Furthermore, the wear marks on the sliding surface 40a act as an abrasive, trying to keep the sliding surface 40a in a stable state. This reduces the amount of liquid leaking, and the process loops back to the first step.

[0051] As shown in FIG. 1, the vertical pump 1 of this embodiment includes a rotating shaft 2 extending vertically, an impeller 3 fixed to the rotating shaft 2, a cylindrical casing 11 housing the impeller 3, a lid portion 32 closing an upper opening of the casing 11, a bracket 31 protruding upward from the lid portion 32 and having a cylindrical portion 33 through which the rotating shaft 2 is inserted, and a mechanical seal 40 sealing a gap between the rotating shaft 2 and the cylindrical portion 33, and a sliding surface 40a of the mechanical seal 40 is located inside the cylindrical portion 33. According to this configuration, the sliding surface 40a of the mechanical seal 40 is located higher than the pump chamber 10A, and the handled liquid in the pump chamber 10A is not supplied to the sliding surface 40a while remaining in a high-temperature and high-pressure state. Therefore, the dry operation state of the sliding surface 40a of the mechanical seal 40 can be suppressed. This reduces the frequency of maintenance of the mechanical seal 40.

[0052] Furthermore, in this embodiment, the cylindrical portion 33 is provided with a second air vent valve 39 at a position equal to or higher than the height of the sliding surface 40a of the mechanical seal 40. With this configuration, priming water can be injected up to the sliding surface 40a of the mechanical seal 40 arranged inside the cylindrical portion 33. Note that the air vent valve 37 provided on the lid portion 32 shown in FIG. 1 may be eliminated and unified with the second air vent valve 39, but the presence of the air vent valve 37 on the lid portion 32 shortens the time required to fill the pump chamber 10A with priming water.

[0053] 2, the present embodiment includes a handled fluid circulation structure 60 that forms a circulating flow that guides the handled fluid inside the casing 11 to the sliding surface 40a of the mechanical seal 40 inside the cylindrical portion 33. With this configuration, new handled fluid can always be supplied to the sliding surface 40a of the mechanical seal 40 located inside the cylindrical portion 33, so that the sliding surface 40a can be prevented from running dry. In addition, since the cylindrical portion 33 protrudes from the cover portion 32 and has a large contact area with the outside air, the handled fluid is cooled in the process of passing through the inside of the cylindrical portion 33. As a result, the sliding surface 40a of the mechanical seal 40 is cooled by the handled fluid, so that the sliding surface 40a is less likely to run dry.

[0054] In this embodiment, the handled liquid circulation structure 60 includes an inner cylinder member 61 that is disposed inside the cylindrical portion 33 and surrounds the outside of the sliding surface 40a of the mechanical seal 40, and a second impeller 62 that is fixed to the rotating shaft 2 and forms a circulation flow with the inside of the inner cylinder member 61 as the outward path and the outside as the return path. With this configuration, by disposing the inner cylinder member 61 inside the cylindrical portion 33 and sending the handled liquid into the inside of the inner cylinder member 61 by the second impeller 62, a circulation flow can be formed in the narrow gap between the cylindrical portion 33 and the mechanical seal 40.

[0055] In the present embodiment, the inner cylinder member 61 is fixed to the bracket 31. With this configuration, the stability of the attachment of the inner cylinder member 61 can be improved.

[0056] Second embodiment Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent configurations as those in the above-described embodiment are given the same reference numerals, and the description thereof will be simplified or omitted.

[0057] FIG. 6 is a cross-sectional view of the vicinity of a cylindrical portion 33 of a vertical pump 1 according to a second embodiment. As shown in FIG. 6, the vertical pump 1 of the second embodiment includes a pumped liquid circulation structure 60 in which an inner cylindrical member 61 is fixed to a second impeller 62 and rotates together with the second impeller 62.

[0058] Fig. 7 is a cross-sectional view of the treated liquid circulation structure 60 according to the second embodiment. Fig. 8 is a plan view of the treated liquid circulation structure 60 according to the second embodiment. 7 and 8, the inner cylinder member 61 is not provided with a flange 61a (see Figs. 2 and 4 described above). The lower end of the inner cylinder member 61 is joined to radially outer ends of the multiple blades 62b of the second impeller 62. The handled liquid passes through the gaps between the multiple blades 62b and passes through the inside of the inner cylinder member 61.

[0059] According to the second embodiment having the above configuration, a circulating flow is formed in the same manner as in the first embodiment, and a dry running state of the sliding surface 40a of the mechanical seal 40 can be suppressed. Moreover, in the second embodiment, the inner cylinder member 61 is fixed to the second impeller 62 and rotates together with the second impeller 62, so there is no need to form an annular groove 11e1 or the like on the bracket 31 side. Furthermore, by integrating the inner cylinder member 61 and the second impeller 62, the number of parts of the handled liquid circulation structure 60 is reduced, making assembly easier.

[0060] Third embodiment Next, a third embodiment of the present invention will be described. In the following description, the same or equivalent configurations as those in the above-described embodiment are given the same reference numerals, and the description thereof will be simplified or omitted.

[0061] FIG. 9 is a cross-sectional view of the vicinity of a cylindrical portion 33 of a vertical pump 1 according to a third embodiment. As shown in FIG. 9, in the vertical pump 1 of the third embodiment, a circulation flow is formed in which the outside of the inner cylindrical member 61 is the forward path and the inside of the inner cylindrical member 61 is the return path when the second impeller 62 rotates.

[0062] The second impeller 62 of the third embodiment is an axial flow fan similar to that of the first embodiment described above, but its orientation is upside down compared to the second impeller 62 of the first embodiment (see FIG. 2 described above). This allows the handled liquid inside the inner cylinder member 61 to be sent to the pump chamber 10A. This allows the handled liquid to be sucked to the outside of the inner cylinder member 61, forming a circulating flow with the outside of the inner cylinder member 61 as the outward path and the inside of the inner cylinder member 61 as the return path.

[0063] According to the third embodiment having the above configuration, the outside of the inner cylinder member 61 close to the cylinder portion 33 that is air-cooled by contact with the outside air becomes the outgoing path of the circulating flow, so the temperature of the handled fluid can be further lowered before it reaches the sliding surface 40a of the mechanical seal 40. This enhances the effect of suppressing the dry operation state of the sliding surface 40a of the mechanical seal 40.

[0064] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. In the following description, the same or equivalent configurations as those in the above-described embodiment are given the same reference numerals, and the description thereof will be simplified or omitted.

[0065] FIG. 10 is a cross-sectional view of the vicinity of a cylindrical portion 33 of a vertical pump 1 according to a fourth embodiment. As shown in Figure 10, in the vertical pump 1 of the fourth embodiment, when the second impeller 62 rotates, a circulation flow is formed with the outside of the inner cylinder member 61 as the forward path and the inside of the inner cylinder member 61 as the return path, and the inner cylinder member 61 is fixed to the second impeller 62 and rotates together with the second impeller 62.

[0066] FIG. 11 is a plan view of a handled fluid circulation structure 60 according to the fourth embodiment. 11, the inner cylinder member 61 is joined to radially outer ends of the multiple blades 62b of the second impeller 62. The blades 62b of the fourth embodiment are circumferentially oriented in the opposite direction to the blades 62b of the second embodiment (see FIG. 8 above), and are capable of delivering the pumped fluid inside the inner cylinder member 61 to the pump chamber 10A.

[0067] According to the fourth embodiment having the above configuration, as in the second embodiment, the inner cylinder member 61 is fixed to the second impeller 62 and rotates together with the second impeller 62, so there is no need to form a fixing structure such as annular groove 11e1 on the bracket 31 side. Furthermore, as the inner cylinder member 61 and the second impeller 62 are integrated, the number of parts of the handled liquid circulation structure 60 is reduced, making assembly easier. Furthermore, according to the fourth embodiment, as in the third embodiment, the outside of the inner cylinder member 61 becomes the outgoing path of the circulating flow, so that the temperature of the handled liquid is lowered, making it easier to cool the sliding surface 40a of the mechanical seal 40.

[0068] Fifth embodiment Next, a fifth embodiment of the present invention will be described. In the following description, the same or equivalent configurations as those in the above-mentioned embodiments are given the same reference numerals, and the description thereof will be simplified or omitted.

[0069] FIG. 12 is a cross-sectional view of the vicinity of a cylindrical portion 33 of a vertical pump 1 according to a fifth embodiment. As shown in FIG. 12, the vertical pump 1 of the fifth embodiment includes a third impeller 70 that is fixed to the rotary shaft 2 and air-cools the cylindrical portion 33 from the outside.

[0070] The third impeller 70 rotates together with the rotating shaft 2, and generates cooling air (indicated by arrows in FIG. 12) toward the inside and outside of the cylindrical portion 33. The third impeller 70 of this embodiment is attached by spot welding to the upper surface of the sleeve holder 51 that fixes the sleeve 49 to the rotating shaft 2. Note that the third impeller 70 may be attached to the sleeve 49 or directly to the rotating shaft 2, for example, as long as it can rotate together with the rotating shaft 2.

[0071] FIG. 13 is a plan view showing a third impeller 70 according to the fifth embodiment. The third impeller 70 has a ring portion 71 with an opening 71a formed in the center, and a plurality of blade portions 72 extending radially outward from the ring portion 71. The ring portion 71 is formed in a flat plate shape. The opening 71a of the ring portion 71 is large enough to allow the rotating shaft 2 to be inserted therethrough. The ring portion 71 has a plurality of joint portions 71b joined to the sleeve holder 51 by spot welding, which are formed at intervals in the circumferential direction. In this embodiment, the joint portions 71b and the blade portions 72 are in phase with each other in the circumferential direction, but they do not have to be in phase with each other.

[0072] The third impeller 70 is attached to the sleeve holder 51 so as to rotate clockwise in the plan view shown in Fig. 13. The blade portion 72 has a flat front edge portion 72a extending radially outward from the outer periphery of the ring portion 71, and a rear edge portion 72b extending obliquely downward from the front edge portion 72a toward the rear side in the rotation direction. As shown in Fig. 12, the rear edge portion 72b is disposed radially outward from the sleeve holder 51 so as not to interfere with the sleeve holder 51. Also, the lower end portion of the rear edge portion 72b is positioned above the head portion of the bolt 46 so as not to interfere with the bolt 46.

[0073] According to the fifth embodiment having the above configuration, as shown in Fig. 12, when the rotating shaft 2 rotates, the third impeller 70 rotates, and cooling air is generated toward the inside and outside of the cylindrical portion 33. The cooling air toward the inside of the cylindrical portion 33 hits the holder 44 and indirectly cools the stationary ring 43 forming the sliding surface 40a by heat conduction through the holder 44. In addition, the cooling air toward the outside of the cylindrical portion 33 flows along the outer wall surface of the cylindrical portion 33 and cools the cylindrical portion 33, thereby indirectly cooling the handled fluid flowing outside the inner cylindrical member 61. This effectively cools the sliding surface 40a of the mechanical seal 40, and more reliably suppresses the dry operation state.

[0074] Although preferred embodiments of the present invention have been described and illustrated above, it should be understood that these are illustrative of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Thus, the present invention should not be considered as limited by the foregoing description, but rather by the scope of the claims. [Explanation of symbols]

[0075] 1 ... vertical pump, 2 ... rotating shaft, 2b ... ring, 3 ... impeller, 4 ... main plate, 5 ... side plate, 6 ... blade, 7 ... suction port, 10A ... pump chamber, 10B ... annular flow passage, 10C ... communication space, 10D ... communication space, 11 ... casing, 11a ... intermediate casing, 11b ... upper casing, 11b1 ... communication hole, 11c ... lower casing, 11c1 ... first frame, 11c2 ... second frame, 11c3 ... communication hole, 11c4 ... flange, 11d ... outer casing, 11e ... casing cover, 11e1 ... annular groove, 12 ... return plate, 13 ... return vane, 14 ... liner ring, 21 ... suction nozzle, 22 ... discharge nozzle, 23 ... pump stand, 23a ... casing bolt, 23b ... nut, 30A ... pump chamber, 31 ... bracket, 32 ... cover, 33...tubular portion, 34...leg portion, 35...base portion, 36...guard member, 37...air vent valve, 38...priming valve, 39...second air vent valve (air vent valve), 40...mechanical seal, 40a...sliding surface, 41...fixed portion, 42...rotating portion, 43...fixed ring, 44...holder, 44a...bottom portion, 44b...side wall portion, 44c...flange portion, 45...O-ring, 46...bolt, 47...rotating ring, 4 8...holder, 49...sleeve, 50...spring, 52...set screw, 60...handled liquid circulation structure, 61...inner cylinder member, 61a...flange, 61b...hole, 62...second impeller, 62a...mounting cylinder, 62b...blade, 70...third impeller, 71...ring, 71a...opening, 71b...joint, 72...blade, 72a...front edge, 72b...rear edge, O...center axis

Claims

1. A rotation axis extending in a vertical direction; An impeller fixed to the rotating shaft; A cylindrical casing that houses the impeller; a bracket having a lid portion that closes an upper opening of the casing, and a tubular portion that protrudes upward from the lid portion and through which the rotating shaft is inserted; a mechanical seal that seals a gap between the rotating shaft and the cylindrical portion, The sliding surface of the mechanical seal is located inside the cylindrical portion, The vertical pump, wherein the cylindrical portion is provided with an air vent plug at a position equal to or higher than the height of the sliding surface of the mechanical seal.

2. a handled fluid circulation structure that forms a circulating flow that guides the handled fluid inside the casing to the sliding surface of the mechanical seal inside the cylindrical portion, The handled liquid circulation structure is 2. The vertical pump according to claim 1, further comprising: an inner cylindrical member disposed inside the cylindrical portion and surrounding an outside of a sliding surface of the mechanical seal; and a second impeller fixed to the rotating shaft and forming the circulating flow with the outside of the inner cylindrical member as a forward path and the inside of the inner cylindrical member as a return path.

3. 3. The vertical pump according to claim 2, wherein the inner cylindrical member is fixed to the bracket.

4. 3. The vertical pump according to claim 2, wherein the inner cylindrical member is fixed to the second impeller and rotates together with the second impeller.

5. 5. The vertical pump according to claim 1, further comprising a third impeller fixed to the rotating shaft for air-cooling the cylindrical portion from the outside.

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